Isolation and partial characterization of a peptidase with trypsin-like activity from bovine adenohypophysis

Abstract

A reproducible method has been developed for the isolation of the adenohypophyseal enzyme with a trypsin-like activity. The enzyme is able to hydrolyze Nα-benzoyl-L-arginine-p-nitroanilide, a fluorogenic substrate CBzl-Arg-Arg-β-naphthyl amide and some peptides with one or two accumulated basic amino acids in the chain. The optimum pH for hydrolysis of the chromogenic substrate was within the range 6.0-7.0 (Km = 0.66 mmol l-1), in the case of the fluorogenic substrate the range was between 7.0 and 7.5 (Km = 1.2 μmol l-1). The enzyme is activated by cysteine and dithiothreitol and inhibited by SH-poisons. The molecular weight of the enzyme, determined by means of two independent methods, was approximately 25 kDA.